In an optical communication system, it is generally necessary to couple an optical fiber to an opto-electronic transmitter, receiver or transceiver device and, in turn, to couple the device to an electronic system such as a switching system or processing system. These connections can be facilitated by modularizing the transceiver device. An opto-electronic transceiver module commonly includes an opto-electronic light source, such as a laser, and an opto-electronic light receiver, such as a photodiode, and may also include various electronic circuitry associated with the laser and photodiode. For example, driver circuitry can be included for driving the laser in response to electronic signals received from the electronic system. Likewise, receiver circuitry can be included for processing the signals produced by the photodiode and providing output signals to the electronic system. Optics such as lenses and reflectors may also be included. Although there are many considerations involved in the design of an opto-electronic transmitter, receiver or transceiver device, one such consideration relates to dissipating heat generated by the laser.
As illustrated in cross section in FIG. 1, a conventional opto-electronic transmitter device 100 includes a housing 112, a laser 114, an integrated circuit chip 116 having driver circuitry for laser 114, and an optical assembly 118. It should be noted that opto-electronic transmitter device 100 is shown in a generalized form in FIG. 1 for purposes of clarity. All but a portion of housing 112 is shown in broken line to indicate that it can have any suitable shape or configuration. For example, housing 112 can have the elongated, rectangular shape associated with the standard configuration commonly referred to in the art as Small Form Factor (SFF) or Small Form Factor Pluggable (SFP). Laser 114 can comprise, for example, a vertical cavity surface-emitting laser (VCSEL). In operation, laser 114 emits light along an axis 115. Optical assembly 118 is made of an optically transparent material and includes a generally cylindrical or barrel-shaped receptacle portion 120 to which an optical plug at the end of a fiber-optic cable (not shown) can be mated. One or more lenses 121 can be included in optical assembly 118, as known in the art.
Laser 114 and integrated circuit chip 116 are sealed within a lower portion 122 of optical assembly 118 that is attached to an upper surface of a printed circuit board 124. Integrated circuit chip 116 is mounted on the upper surface of printed circuit board 124. Laser 114 is mounted on a metal region 126 on the upper surface of printed circuit board 124. Laser 114, integrated circuit chip 116, and electrical connections (not shown) on the surface of printed circuit board 124 are interconnected by wirebonds 127, only one of which is shown for purposes of clarity. A number of vias 128 or metal-plated through-holes filled with a thermally conductive material such as solder extend through printed circuit board 124 between metal region 126 and the lower surface of printed circuit board 124. During operation of laser 114, vias 128 conduct excess heat away from metal region 126, which transmits the excess heat produced by laser 114. A thermal gap pad 130 between an interior wall of housing 112 and the lower surface of printed circuit board 124 transmits the heat from vias 128 to housing 112. Although not shown for purposes of clarity, in operation, when opto-electronic transmitter device 100 is plugged into a bay or port in an electronic system, heat is dissipated from housing 112 by air flow or additional heat sinks that are included in the electronic system.
As illustrated in cross section in FIG. 2, another conventional opto-electronic transmitter device 200 includes a housing 212, a laser 214, an integrated circuit chip 216 having driver circuitry for laser 214, and an optical assembly 218. It should be noted that opto-electronic transmitter device 200 is shown in a generalized form in FIG. 2 for purposes of clarity. All but a portion of housing 212 is shown in broken line to indicate that it can have any suitable shape or configuration. For example, housing 212 can have the shape associated with an SFF or SFP configuration. Laser 214 can comprise, for example, a VCSEL. In operation, laser 214 emits light along an axis 215. Optical assembly 218 is made of an optically transparent material and includes a generally cylindrical or barrel-shaped receptacle portion 220 to which an optical plug at the end of a fiber-optic cable (not shown) can be mated. One or more lenses 221 can be included in optical assembly 218, as known in the art.
Laser 214 and integrated circuit chip 216 are sealed within a lower portion 222 of optical assembly 218 that is attached to an upper surface of a printed circuit board 224. Integrated circuit chip 216 is also mounted on the upper surface of printed circuit board 224. A metal slug 226 extends through printed circuit board 224 between the upper surface and the lower surface. Laser 214 is mounted on a region of metal slug 226 near the upper surface of printed circuit board 224. Laser 214, integrated circuit chip 216, and electrical connections (not shown) on the surface of printed circuit board 224 are interconnected by wirebonds 227, only one of which is shown for purposes of clarity. During operation of laser 214, metal slug 226 conducts excess heat away from laser 214. A thermal gap pad 228 between an interior wall of housing 212 and the lower surface of metal slug 226 transmits the heat from metal slug 226 to housing 212. Although not shown for purposes of clarity, when opto-electronic transmitter device 100 is plugged into a bay or port in an electronic system and is operating, heat is dissipated from housing 212 by air flow or additional heat sinks that are included in the electronic system.